Optimize the Supply Air Temperature Reset Schedule for a Single-Duct VAV System

Abstract

The supply air temperature for a single-duct variable air volume (VAV) system is usually set as a constant. To minimize the simultaneous cooling and heating, this supply temperature is often reset based on either return air temperature or outside air temperature. However, resetting the supply air temperature not only impacts the cooling and heating energy consumption, but also the fan power consumption. If reset improperly, it may cause indoor air humidity problems or result in a fan power consumption penalty. This paper investigates the major factors that impact the optimal supply air temperature reset schedule which minimizes the overall heating energy, cooling energy and fan power consumption. Simulation results are compared for systems with different interior area ratios, load conditions, minimum supply airflow rates, and thermal to electrical energy price ratios.